Many people, especially academics and taxi drivers, take pride in having arcane knowledge at their fingertips. Dr William B Bean bested them all. Dr Bean's arcane knowledge was not only at his fingertips; it was about them. Dr Bean spent much of his adult life monitoring the growth of his fingernails.

Dr William B Bean (born 1909, died 1989) conducted what is known as a longitudinal self-study of fingernail growth. It is one of the few such studies known, and perhaps the lengthiest. Dr Bean taught for many years at the University of Iowa College of Medicine and later at the University of Texas medical branch at Galveston, Texas.

The research was published in the Archives of Internal Medicine, of which Dr Bean happened to be editor.

In 1968, the first of the Bean nail papers arrived in print. Called Nail Growth: Twenty-Five Years' Observation, its timing was unfortunate for Dr Bean, in that the world was distracted by riots, assassinations, the Vietnam war, and the nail-biting American presidential election in which Richard Nixon rose to power. 1974 saw the publication of Dr Bean's extended observations. His paper, entitled Nail Growth: 30 Years of Observation was published just a few weeks after President Nixon's attention-grabbing resignation from the American presidency.

Two years later, Dr Bean published a cuticle-centric essay not in his own journal, but in the International Journal of Dermatology. Under the headline "Some Notes of an Ageing Nail Watcher", he explained that: "Growth of deciduous tissues gives us a natural kymograph to record secular trends and in some instances makes the mark on the moving record. For the observant clinician, knowledge of the rate of nail growth may permit an occasional spectacular diagnosis, although much more often it merely adds a small bit to our understanding of simple biological principles in health and disease."

Thereafter, Dr Bean returned to his original, deliberate publication schedule. In January 1980 he produced Nail Growth: Thirty-Five Years of Observation. It is as complete a story as the world has ever seen about the growth of one physician's fingernails. Here is his summary: "A 35-year observation of the growth of my nails indicates the slowing of growth with increasing age. The average daily growth of the left thumbnail, for instance, has varied from 0.123mm a day during the first part of the study when I was 32 years of age to 0.095mm a day at the age of 67."